Animals make powerful insults precisely because we have imagined them as devoid of subjective and emotional lives that would obligate us to have responsibilities toward them. Animals are a category of beings that in the Western tradition we have decided that we rarely, if ever, have duties toward—we can buy them, sell them, and discard them like objects. To call someone an animal is to render them a being to whom one does not have responsibilities, a being that can be shamelessly objectified.
Perhaps we need to ask how we can assert both our humanity and our animality. How do those of us who have been negatively compared to nonhuman animals assert our value as human beings without implying human superiority or denying our own animality?